In recent years, ferromagnetic dielectric (Multiferroics) materials that make multiple effects in the coexistence of ferromagnetism and ferroelectricity have been attracting attention, and actively researched and developed.
The ferromagnetic dielectric materials are known to induce, when a magnetic field acts thereon, spiral magnetic ordering to produce ferroelectricity, thereby producing electric polarization, or changing the electric polarization or the dielectric constant, and exhibiting a so-called electrical magnetic effect of causing magnetization or making a change in magnetization when an electric field acts thereon.
The ferromagnetic dielectric materials can, by the electrical magnetic effect described above, produce a change in magnetization with an electric field, and a change in electric polarization with a magnetic field, and have been thus expected to be applied to various ceramic electronic components such as a variable inductor that changes in magnetic permeability or magnetization through the application of an electric field, a variable magnetization device for a writing head of a storage medium, or a magnetic sensor that detects magnetism, and further, a non-volatile memory, for example.
Further, Patent Document 1 proposes a multiferroic element configured to control the orientation of electric polarization substantially perpendicular to an external magnetic field through the application of the external magnetic field to a multiferroic solid material that has both ferroelectricity and ferromagnetism with a spin structure where the spin orientation is rotated to follow the outside of a cone (the vertex of the cone has an opening angle α in the range of 0 degrees<α≤90 degrees).
In Patent Document 1 herein, the use of CoCr2O4 (M=Mn, Fe, Co, Ni) as a ferromagnetic dielectric material (multiferroic material) produces electric polarization through the action of a magnetic field in a cryogenic range around 26 K, and achieves electric polarization of 2 μC/m2 around 5 K.
In addition, Patent Document 2 proposes a multiferroic element configured to induce an electric current with a multiferroic solid material including a ferric oxide as a main raw material, which has both ferroelectricity and ferromagnetism, through a weak external magnetic field of 300 G (gauss) or less.
Patent Document 2 herein states that when a low magnetic field of 300 G (0.03 T) is allowed to act with the use of a ferrite compound of Ba2Mg2Fe12O22 as a ferromagnetic dielectric material (multiferroic material), an electric current flows in response to the application of an alternating magnetic field at −268° C. (5 K), and electric polarization is also produced to alternate the positive and negative.
Furthermore, Patent Document 3 proposes an electrical magnetic effect material configured to include, as a main constituent, an oxide ceramic represented by the general formula (Sr1-αBaα)3(Co1-βBβ)2Fe24O41+δ (in the formula, B represents one or more elements selected from the group consisting of Ni, Zn, Mn, Mg, and Cu, and α, β, and δ respectively meet 0≤α≤0.3, 0≤β≤0.3, and −1≤δ≤1), which has an electrical magnetic effect in the temperature range of 250 to 350 K and the magnetic field range of 0.05 T (tesla) or less.
In Patent Document 3 herein, a ferromagnetic dielectric material is achieved which has a region with electric polarization of 1.0 to 9.5 μC/m2 around room temperature and in the magnetic field range of 0.05 T or less, and an electrical magnetic coupling coefficient of 100 ps/m or more, up to 470 ps/m, through the sweep between −0.05 T and +0.05 T with the use of the ferromagnetic dielectric material that has a hexagonal z-type crystal structure represented by the general formula.    Patent Document 1: WO 2007/135817 (claims 1, 3; paragraph number [0031], FIG. 7, etc.)    Patent Document 2: Japanese Patent Application Laid-Open No. 2009-224563 (claims 1, 3; paragraph number [0032], FIG. 7, etc.)    Patent Document 3: Japanese Patent Application Laid-Open No. 2012-1396 (claim 1; paragraph numbers [0010], [0061], Table 3, FIG. 3, etc.)